a) he shoots all his films in the same cave
b) their merits - action, that is - can probably be credited to someone else

This one is a sloppy mini-budget ninja actioner, but comes with an amazing final fight that that rivals anything in The Raid. The honour belongs to Japan's best choreographer Kensuke Sonomura (Hard Revenge Milly: Bloody Battle, Bushido Man), whose work is entertaining, and in case of the 8 min finale, breathtakingly furious, some of the best ever filmed in Japan.

What's best, the fights are expertly captured with clear cinematography and logical editing, unlike some other recent action films (The Raid 2 with its constant shaky cam, John Wick 2 with its nonsensical editing where the viewer can't keep track from which direction the villains are coming). Ninja Hunter's final fight is not only shot with long takes (usually 10-15 punches per shot), but also edited in such a way that every time the there's a cut, the characters remain in the same relation to each other as in the previous shot (i.e. if the bad guy was on the left side of the hero in at the end of the first shot, he will still be on the same side in the beginning of the next shot).

The film also uses the familiar cinematography style from Takanori Tsujimoto's films where the camera is often in slight movement but not in a shaky way, but following the fighter's movements, which makes the fights simultaneously faster and easier to follow.

The storyline is a crossover between Rashomon and Memento, with a ninja (Masanori Mimoto of Alien vs. Ninja) waking up in a cave, minus his memory, and surrounded by corpses. Another ninja (Bushido Man's Mitsuki Koga) shows up, claiming to be a fellow Iga warrior, but something stinks in his story. The rest of the film is spent with the ninja recovering his memory little by little in reverse chronological order. There are some slightly original ideas, such as seeing one fight 4 times from conflicting perspectives, as well as horrible, infuriating visual effects every time the film shows a flashback (which is about 20 times) and lots of bad acting.

Here is the final fight on YouTube. Spoilers naturally, but I'm not sure it matters. I'd recommend taking just a quick peek and then finding a legal way to see the entire film. Here are time codes to two amazing bits: